Generally speaking, a scanner is a device configured to read image data recorded on a document, and may be employed in various apparatuses, such as, for example, a facsimile, a digital photocopier, a multifunctional apparatus, and the like.
A conventional scanner may include a step motor and a DC motor mechanically connected with the step motor. During operation of the conventional scanner, only one of the step motor and the DC motor is driven at a given time. Thus, the conventional scanner selectively drives the step motor or the DC motor in consideration of the demanded resolution, the desired scanning speed, and the like.
However, in such a conventional scanner wherein the step motor and the DC motor are in mechanical connection with each other, a driving force of one of the step motor and the DC motor is transmitted to the other one not in operation, thereby incurring loss of power and increased noise and vibration. For example, when the step motor is driven, the DC motor mechanically connected with the step motor may operate as a load to the step motor. Also, as a rotor of the DC motor is rotated by the driving force transmitted from the step motor, noise and vibration may be generated. Moreover, structural load variation, such as a cogging torque, may be generated in the DC motor according to the position of the rotor. The cogging torque may vary the loads to the step motor, possibly deteriorating the scanning performance. An analogous problem may also occur during driving of the DC motor. Thus, a scanner with an improved driving structure is desired.